Dark-edged bee-fly

Spring is fast approaching and the gloomy days of winter will soon be over meaning our gardens and surroundings will be buzzing with all sorts of weird and wonderful invertebrates! To welcome this seasonal change, our Bug of the Month is the Dark-edged bee-fly. Why you ask? Buglife’s CEO, Matt Shardlow, said recently ‘When I see bee-flies hovering in front of purple ground ivy flowers, drinking nectar with their long straight tongues, then I know that spring has definitely and firmly arrived’. Our Bug of the Month couldn’t have been any other critter!

Fast Facts

Where in the UK: Most common in Southern England, the Midlands and the Welsh lowlands but has also been expanding northwards in recent years as far as north Scotland

Dark-edged bee-flies are very striking invertebrates with adults having a hairy body, long hairy legs and a very long tongue!

That’s a tongue?!

Many people run when they see a Dark-edged bee-fly, convinced it has a huge stinger attached to its face. However, there is no need to make a quick escape as this ‘stinger’ is actually its long tongue (or proboscis if you want to get scientific!) and is used for drinking nectar from deep flowers like Primrose. Adults often hover next to plants and rest two legs on the flower head whilst feeding with their wonderful elongated tongues.

Is it a bee? Is it a fly? It’s a bee mimic!

Dark-edged bee-flies are sneaky critters with devious yet admirable behaviours. They are bee mimics, meaning they resemble small bumblebees yet are actually flies.

Their larvae are parasitoids of the larvae of mining bees which usually nest in colonies in soil such as woodlands or even your flower beds and lawns. Female bee-flies hover a few inches above mining bee nesting areas and flick eggs onto the ground with a rapid twist of the body. They actually collect fine dust in a little chamber at their rear end just prior to this, as the eggs need to be dust-coated before they are laid.

Once a bee-fly egg hatches the larva crawls into the underground nest cell of a host bee. Once the host grub is sufficiently large, the bee-fly larva attaches itself and starts to suck out the body fluids of the host species!

Digging bees are a common host species for large bee-flies.

Sun seekers

Fans of the warmth, Dark-edged bee-flies prefer to fly in sunshine and will often sunbathe on bare ground or dead leaves. They do not usually fly in temperatures less than 17°C, and when it is cold, they will perch vertically pointing upwards. If the weather is really wet, Dark-edged flies need to shelter under leaves as getting wet would kill them. Before take off, adults will whirr their wings to warm up flight muscles.

Where do they live?

The Dark-edged bee-fly is the most common bee-fly species in the UK and lives in a variety of habitats including gardens, alongside hedgerows, in and around woods and around the coast. If it’s good habitat for mining bees, it should be good for bee-flies!

Did you know?

Adult male bee-flies perform courtship rituals to woo their ladies. A male will hover at heights of 2.5 metres and exhibit territorial behaviour such as darting at other males to warn them off and spinning at females to show off.

To find out more about the various bee-fly species we have in the UK or to submit a record of a bee-fly, click here to visit the bee-fly page on the Dipterists Forum.

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